The photoionized emitter can be invoked by typing 'mo photemis'. This model is
the `thermal' (i.e. recombination and collisional excitation) emission which
comes from the same plasma used in warmabs. Note that this does NOT include the
resonant scattered emission associated with the warmabs line emission; the windabs
model can be used, with a trick, to model this emission if desired (see below).

The model supplies to xspec the emissivity of the gas, in units of
erg cm s, times a factor 10. So the physical meaning of the
normalization, , is

(8.1)

where EM is the emission measure of the gas
in the source (at the ionization parameter used in the fit) and D is the distance to
the source. This same relation applies to the results from the hotabs model.